Business (Narratives) (Details)	6 Months Ended
	Jun. 30, 2014 tenant sqft property
Additional disclosures
Number of real estate properties	686
Number of tenants	216
Square footage of real estate properties	81,800,000
Occupancy rate	98.50%
Managed REITs
Additional disclosures
Number of real estate properties	375
Number of tenants	119
Square footage of real estate properties	39,600,000
Occupancy rate	99.96%
Managed REITs | Operating real estate
Additional disclosures
Number of real estate properties	100
Square footage of real estate properties	10,600,000